Rockwell Automation AADvance Controller Safety Manual User Manual
Page 51
Document: 553630
ICSTT-RM446K-EN-P Issue: 10
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3-17
The bindings are based on a producer/consumer model. The controller
consuming the data establishes a binding link with the Controller producing the
data, and manages the entire exchange of data, including scheduling the data
exchange, providing the diagnostics, managing the safety response in the event
of faults and managing the communications redundancy.
SNCP Networks can be configured as Simplex (Fail Safe) or Redundant (Fault
tolerant), the choice of network configuration is dependent on the applications
safety and availability requirements. The data exchange is independent of the
physical; network configuration as the connection between the controllers is
treated as a logical network.
The physical network is considered a "Black Channel" so the design of the
Ethernet network and the equipment used does not impact the SIL rating of
the communications interface, but the design of the network does affect the
reliability of the network and does impact the spurious trip rate. SNCP
Network data can be combined on a common network resulting in safety and
non-safety data sharing in a common physical network; this does not
compromise the SIL rating of the network but again does introduce failure
modes and possibly security risks which can increase the spurious trip rate,
careful consideration should be given to the network topology during the
applications specification and design phase.